The tray of a CD-ROM drive, or by extension the CD drive itself. So
called because of a common tech support legend about the idiot who called
to complain that the cup holder on his computer broke. A joke program was
once distributed around the net called “cupholder.exe”, which
when run simply extended the CD drive tray. The humor of this was of course
lost on people whose drive had a slot or a caddy instead.